Clinoptilolite filled poly(vinylalcohol) membranes containing different weight percentages of zeolite were prepared by solution casting method, and the prepared membranes were characterised by scanning electron microscopy, thermogravimetric analysis and differential scanning calorimeter. Sorption and permeation experiments were carried out at 30, 40 and 50°C in pure water, ethanol (EtOH) and ethylacetate. In addition, the pervaporation separation of EtOH-water mixtures was conducted for 20-80 wt% water containing EtOH-water binary mixtures at 30, 40 and 50°C. It is observed that permeation rates increased and selectivity decreased with the increasing of temperature and the water content in the feed.
Summary: The aim of the study was to investigate the variation in total surface area, porosity, pore size, Knudsen and surface diffusion coefficients, gas permeability and selectivity before and after the application of sol‐gel process to porous ceramic membrane in order to determine the effect of pore modification. In this study, three different sol‐gel process were applied to the ceramic support separately; one was the silica sol‐gel process which was applied to increase porosity, others were silica‐sol dip coating and silica‐sol processing methods which were applied to decrease pore size. As a result of this, total surface area, pore size and porosity of ceramic support and membranes were determined by using BET instrument. In addition to this, Knudsen and surface diffusion coefficients were also calculated. After then, ceramic support and membranes were exposed to gas permeation experiments by using the CO2 gas with different flow rates. Gas permeability and selectivity of those membranes were measured according to the data obtained. Thus, pore surface area, porosity, pore size and Knudsen diffusion coefficient of membrane treated with silica sol‐gel process increased while total surface area was decreasing. Therefore, permeability of ceramic support and membrane treated with silica sol‐gel process increased, and selectivity decreased with increasing the gas flow rate. Also, surface area, porosity, pore size, permeability, selectivity, Knudsen and surface diffusion coefficients of membranes treated with silica‐sol dip coating and silica‐sol processing methods were determined. As a result of this, porosity, pore size, Knudsen and surface diffusion coefficients decreased, total surface area increased in both methods. However, viscous flow and Knudsen flow permeability were detected as a consequence of gas permeability test and Knudsen flow was found to be a dominant transport mechanism in addition to surface diffusive flow owing to the small pore diameter in both methods. It was observed that silica‐sol processing method had lower pore diameter and higher surface diffusion coefficient than silica‐sol dip coating method.
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